One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,5,3)(4,7,8,6)(9,10,16,15)(11,13,20,17)(12,21,14,18)(19,24,22,23)(26,31)(32,38)(33,39)(34,40)(2,3)(6,7)(9,11)(10,17)(12,22)(13,15)(14,19)(16,20)(18,23)(21,24)(25,26)(27,32)(28,33)(29,34)(30,31)(35,39)(36,38)(37,40) involution — undirected(1,3,5,2)(4,7,8,6)(9,12,16,14)(10,18,15,21)(11,19,20,22)(13,23,17,24)(25,27,30,36)(26,32,31,38)(28,29,35,37)(33,34,39,40)(1,4)(2,6)(3,7)(5,8)(9,13)(10,11)(12,23)(14,24)(15,20)(16,17)(18,19)(21,22)(25,26)(27,32)(28,33)(29,34)(30,31)(35,39)(36,38)(37,40) involution — undirected(9,14,16,12)(10,18,15,21)(11,19,20,22)(13,24,17,23)(25,28)(26,33)(27,29)(30,35)(31,39)(32,34)(36,37)(38,40)(9,15,16,10)(11,13,20,17)(12,21,14,18)(19,23,22,24)(25,29)(26,34)(27,35)(28,36)(30,37)(31,40)(32,39)(33,38)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.