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