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