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