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)(11,15)(12,22)(13,16)(14,17)(18,19)(20,24)(21,23)(25,26)(27,36)(28,39)(29,35)(30,34)(31,33)(32,38)(37,40) involution — undirected(1,3,5,4)(2,6,8,7)(9,11)(10,15)(12,18)(13,20)(14,21)(16,24)(17,23)(19,22)(25,27,30,38)(26,32,34,36)(28,31,37,29)(33,39,35,40)(1,3,5,4)(2,7,8,6)(9,12,22,10,14,16,13,17)(11,18,19,15,21,24,20,23)(25,28,31,38,30,37,29,27)(26,32,35,39,34,36,33,40)(1,4,5,3)(2,7,8,6)(9,13,14,22)(10,16,17,12)(11,19,21,20)(15,18,23,24)(25,29,30,31)(26,33,34,35)(27,37,38,28)(32,40,36,39)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.