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