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