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