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