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