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