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