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