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