One vertex per element, one color per generator, with an edge from x to x·s.
(9,10,13,17)(11,16,20,14)(12,21,22,15)(18,23,19,24)(26,31)(28,35)(32,40)(36,38)(1,2)(3,8)(4,6)(5,7)(9,11)(10,14)(12,18)(13,20)(15,23)(16,17)(19,22)(21,24)(26,31)(27,33)(32,40)(34,37) involution — undirected(1,3,5,6)(2,4,7,8)(9,12)(10,15)(11,18)(13,22)(14,23)(16,24)(17,21)(19,20)(25,26)(27,28)(29,32)(30,31)(33,35)(34,36)(37,38)(39,40)(1,2)(3,4)(5,7)(6,8)(9,12)(10,15)(11,19)(13,22)(14,24)(16,23)(17,21)(18,20)(25,27)(26,28)(29,37)(30,33)(31,35)(32,38)(34,39)(36,40) involution — undirected(1,2)(3,4)(5,7)(6,8)(9,10)(11,14)(12,15)(13,17)(16,20)(18,23)(19,24)(21,22)(25,28)(26,27)(29,38)(30,35)(31,33)(32,37)(34,40)(36,39) involution — undirected(1,4)(2,6)(3,7)(5,8)(9,11)(10,16)(12,18)(13,20)(14,17)(15,24)(19,22)(21,23)(25,29,30,39)(26,32,31,40)(27,34,33,37)(28,36,35,38)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.