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