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