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