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