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