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)(11,12)(13,17)(14,15)(16,20)(18,19)(21,22)(23,24)(25,26)(27,31)(28,29)(30,38)(32,34)(33,39)(35,36)(37,40)(1,3,5,8)(2,6,4,7)(25,27,32,29)(26,31,34,28)(30,35,39,37)(33,40,38,36)(1,4,5,2)(3,7,8,6)(10,15)(11,16)(17,22)(18,23)(25,28,32,31)(26,27,34,29)(30,36,39,40)(33,35,38,37)(9,11,14,16)(10,12,15,20)(13,18,21,23)(17,19,22,24)(25,29,32,27)(26,28,34,31)(30,37,39,35)(33,36,38,40)(9,12)(10,16)(11,15)(13,19)(14,20)(17,23)(18,22)(21,24)(25,30)(26,33)(27,35)(28,36)(29,37)(31,40)(32,39)(34,38) involution — undirected(9,13,14,21)(10,17,15,22)(11,18,16,23)(12,19,20,24)(25,31,32,28)(26,27,34,29)(30,36,39,40)(33,37,38,35)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.